Function string_to_u64

perro_source/core/perro_ids/src/ids.rs:12–40

(s: &str)

#[inline]
pub const fn string_to_u64(s: &str) -> u64 {
    let bytes = s.as_bytes();
    let len = bytes.len();
    if len == 0 {
        return EMPTY_STRING_HASH;
    }

    let mut hash = STRING_HASH_SEED ^ (len as u64).wrapping_mul(STRING_HASH_PRIME);
    let mut i = 0usize;

    while i + 8 <= len {
        hash ^= read_u64_le(bytes, i);
        hash = hash.wrapping_mul(STRING_HASH_PRIME);
        hash ^= hash >> 32;
        i += 8;
    }

    let mut tail = 0u64;
    let mut shift = 0u32;
    while i < len {
        tail |= (bytes[i] as u64) << shift;
        shift += 8;
        i += 1;
    }

    hash ^= tail;
    hash = hash.wrapping_mul(STRING_HASH_SEED);
    mix64(hash)
}

const fn read_u64_le(bytes: &[u8], offset: usize) -> u64 {
    (bytes[offset] as u64)